Home-made Lathe Rest Lock

Recently, my brother and I were given and old Craftsman Lathe. It was well used and needed a lot of work- of which one thing that it needed was a new lock for the rest. Apparently, at some point in time, it had broken off and the first owner had simply cut a slot in the broken area for a flat head screw-driver. After removing the broken screw, I took a carriage bolt and put the hand tightener on it then locked two nuts together. Now I have the perfect lock for the rest and spent practically nothing!